JP6962713B2 - sewing machine - Google Patents

Description

The present invention relates to a sewing machine that detects the amount of movement of an object to be sewn relative to the sewing machine.

Conventionally, the amount of movement of the sewn object on the needle plate is determined by an optical sensor fixedly mounted on the frame of the sewing machine, and the rotation speed of the sewing machine motor is controlled so that the needle drops with a constant amount of movement. , A sewing machine that maintains a constant sewing pitch is known (see, for example, Patent Document 1).

Japanese Patent No. 4724938

However, in the above-mentioned conventional sewing machine, as shown in FIG. 7A, when the sewing needle 112 is located above the sewn object, the sensor 121 determines the movement amount m of the sewn object C. Although it can be detected correctly, when the sewing needle 112 is pierced by the sewn object C, the movement of the sewn object C is restricted, so that the sensor 121 accurately detects the movement amount of the sewn object. I couldn't.
In particular, when the sewing needle 112 passes through the bottom dead center and rises, as shown in FIG. 7B, the sewing object C is pulled up together with the sewing needle 112. The moving component mf was generated in the object C, and the sensor 121 further lowered the detection accuracy of the moving amount of the sewn object.

An object of the present invention is to detect the amount of movement of the sewn object while avoiding the influence of needle dropping of the sewn object.

The invention according to claim 1 is used in a sewing machine.
A movement amount detection unit that detects the movement amount of the sewn object,
A sewing machine motor that serves as a rotational drive source for the upper shaft that gives vertical movement to the needle bar,
A shaft angle detection unit that detects the shaft angle of the upper shaft or the output shaft of the sewing machine motor, and
In a sewing machine including a control device that controls the sewing machine motor based on the detection of the movement amount detection unit and controls to maintain a constant sewing pitch.
Based on the detection of the axial angle detecting unit, the control device has a constant sewing pitch based on the moving amount of the sewn object detected by the moving amount detecting unit in the axial angle section where the sewing needle is not pierced into the fabric. Control to maintain.

In the above sewing machine
The control device can set a predetermined range of the upper axis angle as a non-detection section among the axial angle sections in which the sewing needle does not pierce the fabric, and the sewing needle excluding the non-detection section pierces the fabric. It is also possible to control to maintain a constant sewing pitch according to the movement amount of the sewn object detected by the movement amount detection unit in the section where there is no movement amount.

Further, the invention according to claim 1 is
It is characterized in that the sewing machine is manually moved with respect to the needle drop position of the sewing machine to perform free motion sewing.
Further, the invention according to claim 2 is
It is characterized in that the sewing machine is manually moved with respect to the object to be sewn to perform free motion sewing.

In the present invention, the control device controls to maintain a constant sewing pitch based on the amount of movement of the sewing object detected in the axial angle section in which the sewing needle does not pierce the fabric, so that the sewing object is more accurately sewn. It is possible to detect the amount of movement of the sewing machine, and it is possible to perform sewing while maintaining a constant sewing pitch with higher accuracy.

It is a perspective view of the sewing machine which is an embodiment of the invention. It is a block diagram which shows the control system of a sewing machine. It is explanatory drawing which shows the range of the upper axis angle which becomes the detection section which acquires the output of each sensor. It is a flowchart which shows the operation control at the time of sewing by a control device. It is explanatory drawing which shows the other example of the detection section. It is explanatory drawing which shows the further other example of the detection section. FIG. 7A is an explanatory diagram showing a moving state of the fabric when the sewing needle is not pierced by the fabric, and FIG. 7B is an explanatory diagram showing a moving state of the fabric when the sewing needle is pierced by the fabric.

[Outline of Embodiment of the Invention]
Hereinafter, the sewing machine according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the sewing machine 100, and FIG. 2 is a block diagram showing a control system of the sewing machine 100.
In the sewing machine 100 of the present embodiment, the operator can freely move the fabric C as an object to be sewn held on a dedicated holding table by a manual operation, and the fabric C is positioned relative to the needle drop position. It is a sewing machine that can perform so-called free motion sewing.
In this embodiment, the illustration of the holding table and the description of the structure are the same as those of the well-known holding table, and thus the description thereof will be omitted.

The sewing machine 100 includes a needle bar vertical movement mechanism that moves the needle rod 13 that holds the sewing needle 12 at the lower end, a kettle mechanism that captures the needle thread passed through the sewing needle 12 and entangles it with the bobbin thread, and a needle thread. A balance mechanism that pulls up to form a knot, a thread tensioner that applies a predetermined tension to the needle thread, a sewing machine frame 11 that stores or holds these, and a control device 90 as a control unit that controls the operation of each part. It has.
Since the hook mechanism, the balance mechanism, and the thread tensioner have the same configuration as a well-known structure in a sewing machine, detailed description thereof will be omitted.

The sewing machine frame 11 includes a sewing machine bed portion located at the lower part of the sewing machine body, a standing body portion erected from one end of the sewing machine bed portion, and a sewing machine arm portion extending from the standing body portion in the same direction as the sewing machine bed portion. It consists of.
In the following description, the horizontal direction along the longitudinal direction of the sewing machine bed portion 111 is the X-axis direction, and the horizontal direction perpendicular to the X-axis direction is the Y-axis direction, the X-axis direction, and the Y-axis direction. The vertical vertical direction orthogonal to is defined as the Z-axis direction.

The needle bar vertical movement mechanism converts the torque of the sewing machine motor 30, which is a drive source for the sewing operation, the upper shaft (not shown), which is rotationally driven by the sewing machine motor 30, into the vertical reciprocating motion, and the needle bar 13 It is equipped with a crank mechanism (not shown).
The output shaft of the sewing machine motor 30 is equipped with an encoder 31 as a shaft angle detection unit, and pulse output is performed according to the amount of change in the shaft angle of the output shaft.
The transmission ratio from the output shaft of the sewing machine motor 30 to the upper shaft is known, and the control device 90 calculates the shaft angle of the output shaft of the sewing machine motor 30 from the pulse output of the encoder 31 and further, from the transmission ratio, the transmission ratio of the upper shaft. The axis angle can be calculated.
An encoder may be provided on the upper shaft to directly detect the axis angle of the upper shaft.

Further, the sewing machine 100 includes an intermediate presser 14 that presses the fabric C so that the sewing needle 12 can be smoothly removed from the fabric C when the sewing needle 12 is raised. The center press 14 is supported by the lower end portion of the center press rod 141. The center press 14 is a small frame body into which the sewing needle 12 can be loosely inserted, and is powered by a sewing machine motor 30 (see FIG. 2), which is a drive source for moving the needle bar 13 up and down, via a well-known transmission mechanism. Is obtained, and the needle bar 13 is moved up and down with an amplitude smaller than that of the needle bar 13. The center retainer 14 is out of phase with the needle bar 13, and the center retainer 14 is lowered when the sewing needle 12 is raised. Further, the center retainer 14 is set so as to have a slight gap with respect to the needle plate 16 at the bottom dead center position so as not to hinder the movement of the fabric C.

Further, as shown in FIG. 2, the sewing machine 100 includes a thread trimming device 43 that cuts the sewing thread at the end of sewing. The thread trimming device 43 includes a moving scalpel capable of reciprocating to pass under the needle plate 16 so as to pass directly under the needle hole, and a fixed scalpel for cutting the sewing thread in cooperation with the moving scalpel. (Both are not shown), the thread trimming motor 431 that reciprocates the moving scalpel, and the drive circuit 432 that drives the thread trimming motor 431 in accordance with the command of the control device 90 are provided.

Further, the sewing machine bed portion 111 is provided on both sides of the needle hole (not shown) of the needle plate 16 in the X-axis direction in the vicinity of the needle drop position of the sewing machine 100 with respect to the fabric C manually sent, and is a horizontal plane (X-). The first and second sensors 21 and 22 are provided as movement amount detection units for detecting the relative movement amount in the Y plane), respectively.
These first and second sensors 21 and 22 are two-dimensional image sensors fixedly mounted in a state of being directed upward from the upper surface of the needle plate 16.

Further, the first and second sensors 21 and 22 are arranged so that their optical axes are parallel to the Z-axis direction and symmetrical with respect to the plane including the center line of the needle bar 13.
The resolution of each of these sensors 21 and 22 is 3 [μm]. Further, each of the sensors 21 and 22 detects the lower surface of the fabric C on the needle plate 16 at any time, and inputs the detection data to the processing device 23 provided therewith.
The numerical values of the resolutions of the sensors 21 and 22 are examples and are not limited to the above numerical values.

The processing device 23 attached to the first and second sensors 21 and 22 has a resolution of 3 [μm] regarding the amount of movement of the fabric C from the continuous detection signals input from the sensors 21 and 22 at any time. A pulse signal is input to the control device 90 each time a change occurs.
The processing device 23 predetermines that one of the first and second sensors 21 and 22 is the main sensor and the other is the sub sensor, and inputs a pulse signal based on the detection of the main sensor to the control device 90. When an error occurs in the main sensor, a pulse signal based on the detection of the sub sensor is input to the control device 90.

[Sewing machine control system]
The sewing machine 100 includes a control device 90 that controls the operation of each configuration, and the sewing machine motor 30 and its encoder 31 described above are connected to the control device 90 via a drive circuit 32.
Further, the thread trimming motor 431 of the thread trimming device 43 described above is connected to the control device 90 via the drive circuit 432, and the first and second sensors 21 and 22 described above are connected via the processing device 23. Has been done.

Further, the operation panel 41 as an operation means for the sewing machine operator to input the operation to the sewing machine, the start button 42 for starting sewing, and the pedal 44 for driving the sewing machine motor 30 are respectively attached to the control device 90. It is connected via an interface (not shown).
From the operation panel 41, for example, the sewing pitch, which is the length of the stitch for each stitch, is set. In addition, the operation panel 41 is provided with a display unit to display various types of information.

The control device 90 mainly stores a CPU 91 that controls the sewing machine motor 30, a RAM 92 that serves as a work area for the CPU 91, a ROM 93 that stores a program processed by the CPU 91, and data used for arithmetic processing. It is provided with an EEPROM 94 as a storage unit configured so that the data can be rewritten.

[Operation control during sewing]
Next, the sewing operation control performed by the control device 90 of the sewing machine 100 will be described.
As described above, the sewing machine 100 is sewn while the sewing machine manufacturer arbitrarily moves the fabric C with respect to the needle drop position.
The control device 90 maintains the constant sewing pitch set from the operation panel 41 when the fabric C is arbitrarily moved and operated by the sewing machine operator, so that the sewing machine motor 30 rotates at a rotational speed. To control.

That is, the control device 90 calculates the moving speed of the fabric C from the time interval (referred to as the pulse interval) of the pulses input based on the detection of the first or second sensors 21 and 22, and further, the moving speed. The rotation speed of the sewing machine motor 30 for the upper shaft to make one rotation before the movement of the sewing pitch set in is performed is calculated, and the rotation speed is controlled to be the rotation speed. The calculation of the rotation speed of the sewing machine motor 30 based on the detection of the first or second sensors 21 and 22 is repeatedly executed in a minute time cycle.

By the way, from the time when the sewing needle 12 is pierced into the cloth C until it is completely removed, the movement of the cloth C is restrained by the sewing needle 12, and it becomes difficult to obtain an accurate moving speed of the cloth C.
FIG. 3 is an explanatory view showing an upper axis angle until the descending sewing needle 12 reaches the needle plate 16 and the sewing needle 12 ascending after passing the needle bar bottom dead center reaches the needle plate 16. The upper axis angle, which is the top dead center of the needle bar, is 0 °, and the upper axis angle, which is the bottom dead center of the needle bar, is 180 °.
As shown in this figure, the upper axis angle at which the descending sewing needle 12 reaches the needle plate 16 is 90 °, and the sewing needle 12 ascending after passing the lower dead point of the needle bar reaches the needle plate 16. The axis angle is 270 °.

Therefore, the control device 90 avoids an axial angle section (referred to as a non-detection section N) having an upper axial angle of 90 ° or more and 270 ° or less, which makes it difficult to obtain an accurate moving speed of the fabric C, and has an upper axial angle of 270. The moving speed of the fabric C is determined from the time interval of the pulse input from the processing device 23 of the first or second sensors 21 and 22 in the axial angle section (referred to as the detection section S) exceeding ° and less than 90 °. ..
The "detection section" means an upper axis angle section that controls the rotation speed of the sewing machine motor 30 based on the detection of the first or second sensors 21 and 22, and the "non-detection section" is the first or second. It means an upper axis angle section in which the rotation speed of the sewing machine motor 30 is controlled without being based on the detection of the second sensors 21 and 22.
In this case, the moving speed of the fabric C cannot be obtained while the upper axis angle is in the non-detection section N. Therefore, the control device 90 considers that the moving speed of the fabric C in the non-detection section N is, for example, that the cloth C is moving at the moving speed obtained immediately before entering the non-detection section N, and the sewing machine motor. The rotation speed of 30 is controlled.
The moving speed of the fabric C in the non-detection section N is not the moving speed of the fabric C obtained immediately before entering the non-detection section N, but other appropriate values may be adopted. For example, the average value of the moving speeds of the plurality of fabrics C calculated in the detection section S may be adopted.
Further, the rotation speed of the sewing machine motor 30 is obtained by multiplying the moving speed of the cloth C obtained immediately before and the averaged moving speed of the cloth C by a predetermined coefficient as the moving speed of the cloth C in the non-detection section N. You may control the speed.

FIG. 4 is a flowchart showing a process executed by the CPU 91 of the control device 90 at the time of sewing. Based on this, the process executed by the CPU 91 at the time of sewing will be described in detail.

First, the CPU 91 initially detects the depression of the pedal 44 (step S1), and if not detected, detects the depression of the pedal 44 again (step S1: NO). Further, when the depression of the pedal 44 is detected (step S1: YES), the driving of the sewing machine motor 30 is started (step S3).

Then, the CPU 91 determines from the output of the encoder 31 whether or not the upper axis angle is within the detection section S (step S5), and if it is within the detection section S (step S5: YES), first or The moving speed of the fabric C is calculated from the time intervals of the pulses of the second sensors 21 and 22 (step S7), and the rotation speed of the sewing machine motor 30 corresponding to the moving speed is calculated (step S9). Further, the CPU 91 controls the sewing machine motor 30 so as to have the calculated rotation speed (step S11).
After that, the process proceeds to step S15.

On the other hand, when the output of the encoder 31 is determined to be outside the detection section S (step S5: NO), the CPU 91 controls the sewing machine motor 30 so as to have the latest rotation speed calculated within the detection section S (step S5: NO). Step S13).
After that, the process proceeds to step S15.

In step S15, the depression of the pedal 44 is detected, and if the depression of the pedal 44 is continued (step S15: NO), the process is returned to step S5, and the upper axis angle is within the detection section S again. It is determined whether or not it is.
When the pedal 44 is released (step S15: YES), the CPU 91 stops the sewing machine motor 30 and ends the operation control.

[Technical Effects of Embodiments of the Invention]
In the sewing machine 100, the control device 90 uses the detection of the encoder 31 as the shaft angle detection unit to detect the movement amount detection unit in the detection section S, which is the shaft angle section in which the sewing needle 12 does not pierce the fabric C. Control is performed to maintain a constant sewing pitch according to the amount of movement of the fabric C detected by the first or second sensors 21 and 22.
Therefore, the sewing machine motor 30 can be controlled more accurately by reducing the influence of the inaccurate movement amount of the fabric C detected in the non-detection section N, which is the axial angle section in which the sewing needle 12 pierces the fabric C. It is possible to perform sewing while maintaining the target sewing pitch.
Therefore, when the fabric C is manually moved to perform free motion sewing as in the sewing machine 100, it is possible to improve the sewing quality in particular.

[About the range of the detection section of the upper axis angle]
The setting of the detection section S is not limited to the section of 90 to 270 ° shown in FIG. 3, and may be a narrower range. In the present embodiment, the upper axis angle range in which the sewing needle 12 is located below the needle plate 16 is defined as the section from when the sewing needle 12 pierces the fabric C until it comes out. For example, as shown in FIG. Considering the thickness of the fabric C, the range of the upper axis angle at which the sewing needle 12 is higher than the needle plate 16 may be set as the detection section S.

Further, the detection section S is not limited to one, and a plurality of detection sections S may be set. For example, in addition to the range of the upper axis angle at which the sewing needle 12 is pierced into the fabric C, the upper axis angle at which the detection accuracy of the moving speed of the fabric C is lowered is known theoretically or empirically, for example. The range of such an upper axis angle may be newly set as a non-detection section, and a plurality of detection sections may be set accordingly.
For example, around the top dead center of the sewing needle 12, when it is known that the detected moving speed of the fabric C is disturbed, as shown in FIG. 6, the upper shaft through which the sewing needle 12 pierces the fabric C. The angle is defined as the first non-detection section N1, and the vicinity of the top dead center of the sewing needle 12 is defined as the second non-detection section N2. Then, the upper axis angle between the first non-detection section N1 and the second non-detection section N2 may be set as the first detection section S1 and the second detection section S2.
As a result, it is possible to reduce the influence of the inaccurate movement amount of the fabric, control the sewing machine motor 30, and more accurately maintain the target sewing pitch for sewing.

Further, it may be possible to set an arbitrary range of the upper axis angle as the non-detection section within the range of the upper axis angle in which the sewing needle 12 is not pierced by the cloth C by the setting means such as the operation panel 41. Further, the number of detection sections may be arbitrarily set.

[others]
The sewing machine 100 exemplifies the case where the fabric C is manually moved with respect to the sewing machine 100, but it goes without saying that the sewing machine 100 may be manually moved with respect to the fabric C to perform free motion sewing.

12 Sewing needle 13 Needle bar 16 Needle plate 21 First sensor (movement amount detection unit)
22 Second sensor (movement amount detection unit)
30 Sewing machine motor 31 Encoder (axis angle detector)
90 Control device 100 Sewing machine C Cloth (sewing)
S, S1, S2 detection section N, N1, N2 non-detection section

Claims (3)

A movement amount detection unit that detects the movement amount of the sewn object,
A sewing machine motor that serves as a rotational drive source for the upper shaft that gives vertical movement to the needle bar,
A shaft angle detection unit that detects the shaft angle of the upper shaft or the output shaft of the sewing machine motor, and
In a sewing machine including a control device that controls the sewing machine motor based on the detection of the movement amount detection unit and controls to maintain a constant sewing pitch.
Based on the detection of the axial angle detecting unit, the control device has a constant sewing pitch based on the moving amount of the sewn object detected by the moving amount detecting unit in the axial angle section where the sewing needle is not pierced into the fabric. have line control to maintain,
A sewing machine characterized in that the sewing machine is manually moved with respect to the needle drop position of the sewing machine to perform free motion sewing. A movement amount detection unit that detects the movement amount of the sewn object,
A sewing machine motor that serves as a rotational drive source for the upper shaft that gives vertical movement to the needle bar,
A shaft angle detection unit that detects the shaft angle of the upper shaft or the output shaft of the sewing machine motor, and
In a sewing machine including a control device that controls the sewing machine motor based on the detection of the movement amount detection unit and controls to maintain a constant sewing pitch.
Based on the detection of the axial angle detecting unit, the control device has a constant sewing pitch based on the moving amount of the sewn object detected by the moving amount detecting unit in the axial angle section where the sewing needle is not pierced into the fabric. have line control to maintain,
A sewing machine characterized in that the sewing machine is manually moved with respect to the object to be sewn to perform free motion sewing. The control device can set a predetermined range of the upper axis angle as a non-detection section among the axial angle sections in which the sewing needle does not pierce the fabric, and the sewing needle excluding the non-detection section pierces the fabric. The sewing machine according to claim 1 or 2 , wherein the sewing machine is controlled to maintain a constant sewing pitch according to the movement amount of the sewn object detected by the movement amount detection unit in a section not provided.

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